ORIGINAL ARTICLE Journal of the College of Physicians and Surgeons Pakistan 2021, Vol. 31(05): 511-516 511 Relationship between Lymph Node Metastasis and a Low 18F-FDG PET/CT Axillary SUVmax Value in Breast Cancer Ozgur Kulahci 1 , Oktay Irkorucu 2 , Emel Kocyigit Deveci 3 and Zeynel Abidin Tas 1 1 Department of Pathology, University of Health Sciences, Adana City Education and Research Hospital, Turkey 2 Department of Surgery, University of Sharjah, College of Medicine, Clinical Sciences, Sharjah, UAE 3 Department of Nuclear Medicine, University of Health Sciences, Adana City Education and Research Hospital, Turkey ABSTRACT Objective: To evaluate breast cancer patients with low F18-fluorodeoxy-glucose positron emission tomography/computed tomography scan (FPET) of axilla standardised maximum uptake value (SUVmax) along with their histopathological findings regarding axillary lymph node metastasis (LNM). Study Design: A descriptive study. Place and Duration of the Study: Adana City Education and Research Hospital, Turkey, from January 2015 to October 2018. Methodology: The current study analysed the findings of 113 patients according to age, histopathological axillary LNM, estrogen and progesterone receptor status, tumour size, histological grade, Ki-67, HER2 and preoperative FPET SUVmax findings. Histopathological and immunohistochemical comparisons were made between FPET axilla SUVmax and univariate and multivariate parameters in breast carcinoma in terms of LNM. Results: The authors analysed the receiver operator characteristic curve for the FPET axilla SUVmax and set the cut-off value to 1.84 to predict LNM. However, it was also found that the SUVmax detected metastases in the axilla at values lower than 1.84. In the multivariate analysis, a statistically significant relationship was found between axilla LNM cases that have FPET axilla SUVmax less than 1.84, a Ki-67 index greater than 15% and tumour size greater than 2 cm (p <0.05). Conclusion: Values that were above the axilla SUVmax limit of 1.84 in FPET helped determine LNM. However, further evalua- tion of patients is needed comparing axilla SUVmax of less than 1.84 in FPET together with the Ki-67 proliferation index and tumour size. Key Words: Breast, Cancer, Lymph nodes, Metastasis, PET, Pathology. How to cite this article: Kulahci O, Irkorucu O, Deveci EK, Tas ZA. Relationship between Lymph Node Metastasis and a Low 18F-FDG PET/CT Axillary SUVmax Value in Breast Cancer. J Coll Physicians Surg Pak 2021; 31(05):511-516. INTRODUCTION Breastcanceristhemostcommonfemalecancerglobally. 1 The absence of axillary LNM is the most critical prognostic survival factor for breast cancer patients. 2 Other prognostic factors, such as tumour size, histopathological grade, and estrogen receptor (ER) status can be determined using imaging methods, histo- pathological examination and immunohistochemical staining, respectively.Axillarylymphnodemetastasescanalsobedeter- mined with radiology and histopathology. For early-stage breast cancer, the most accepted method for detecting LNM is surgical axillary lymph node dissection (ALND), sentinel lymph node biopsy (SLNB). 3 Correspondence to: Dr. Ozgur Kulahci, Department of Pathology, University of Health Sciences, Adana City Education and Research Hospital, Turkey E-mail: ozgurkulahci@hotmail.com ..................................................... Received: July 01, 2020; Revised: March 25, 2021; Accepted: April 15, 2021 DOI: https://doi.org/10.29271/jcpsp.2021.05.511 Sophisticated imaging methods such as breast magnetic reso- nance imaging, ultrasonography, and F18-fluorodeoxy-glu- cose positron emission tomography combined with CT (FPET) are also used preoperatively to identify axillary LNM. FPET is recommended for advanced breast carcinoma and is influen- tialindeterminingaxillaryLNM,especiallyifthecancerisinan advanced regional stage or a distant metastatic state. 4 FPET has been reported to have different specificity and sensitivity valuesinvariousstudies. 5-10 While increased axilla FPET standardised maximum-uptake-- value(SUVmax)isavaluablemeasureofLNM,tumourmetas- tasiscanstillbeseeninpatientswithalowerSUVmax. The objective of this study was to analyse the relationship between low SUVmax and the histopathological findings of tumourmetastasis. METHODOLOGY Thestudyincluded113casesthatwereundergoingapreopera- tive FPET scan, then breast surgery, followed by pathological axillary lymph node evaluation between January 2015 and